Install new cab over curtain in a Bigfoot TC, HOW?

Bigfoot has ducting in cabover, so airflow not a problem. “Mouse fur” on ceiling, so Velcro won’t work unless curtain is exceedingly light. Yes, attempting to cross spam entering the cabover in my Truck camper. Problem isn’t finding track or way to hang a curtain, but how to mount to ceiling, as it is a fiberglass shell. I don’t know what I am screwing into (insulation, wood) or the depth I have to use.